A time-domain fault location method and system for high-voltage transmission lines

Abstract

The application discloses a time-domain fault location method and system for a high-voltage transmission line, and the method comprises the following steps: acquiring and establishing a telegraph equation of the transmission line according to the line structure and the transmission line parameters of the high-voltage transmission line; performing difference discretization on the telegraph equation of the transmission line in the time domain to establish a first-order differential equation; performing matrix conversion on the first-order differential equation to obtain a matrix form equation, and performing space integral conversion on the matrix form equation to obtain a space integral equation; and measuring the fault point position of the high-voltage transmission line according to the space integral equation and the synchronous measurement information of the two ends of the fault line through the voltage continuity principle along the transmission line. The embodiment realizes efficient determination of the fault point position, is not affected by calculation conditions such as difference format and step length, and has high location accuracy.

Description

Technical Field

[0001] This invention relates to the field of fault location in high-voltage transmission lines, and more particularly to a time-domain fault location method and system for high-voltage transmission lines. Background Technology

[0002] High-voltage transmission lines are the lifeblood of the power system, and also the most frequent sites of faults, which are extremely difficult to locate. Fault location is an inspection technique for high-voltage transmission lines, also known as fault localization, which refers to determining the location of the fault point. Quickly and accurately locating the fault point after a line fault occurs is crucial not only for timely line repair and ensuring reliable power supply, but also for the safe, stable, and economical operation of the power system. Therefore, rapid and accurate fault location methods for transmission lines have always been a research hotspot in the power system field.

[0003] Currently, the main methods for fault location in transmission lines include the frequency domain method, the traveling wave method, and the time domain method. While the frequency domain method is simple and reliable, it is easily affected by factors such as transition resistance, sampling frequency, and line symmetry, making it difficult to guarantee measurement accuracy. The traveling wave method is unaffected by transition resistance and has high location accuracy, but the wavefront is difficult to extract accurately, and the wave velocity is also difficult to determine accurately. Furthermore, the equipment is expensive, limiting its application. The time domain method utilizes transient information during a line fault, establishing a time-domain differential equation containing fault information based on circuit theory. By performing differential calculations on this time-domain equation, the fault location of the transmission line can be determined. However, its accuracy and stability are greatly affected by the differential scheme and step size, and are influenced by computational conditions, lacking stability and unable to guarantee accuracy. Summary of the Invention

[0004] This invention provides a time-domain fault location method and system for high-voltage transmission lines, which enables efficient determination of fault location, is unaffected by calculation conditions such as differential scheme and step size, and has high ranging accuracy.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a time-domain fault location method for high-voltage transmission lines, comprising:

[0006] Based on the line structure and transmission line parameters of the high-voltage transmission line, establish the transmission line telegraph equation;

[0007] The transmission line telegraph equations are discretized by difference in the time domain to establish a first-order differential equation;

[0008] The first-order differential equation is transformed into a matrix form to obtain a matrix form equation, and then the matrix form equation is transformed into a space integral equation to obtain a space integral equation.

[0009] By utilizing the principle of voltage continuity along the transmission line, and based on synchronous measurement information at both ends of the faulty line and spatial integral equations, the location of the fault point in the high-voltage transmission line can be measured.

[0010] This invention involves acquiring and establishing transmission line telegraphic equations based on the line structure and parameters of a high-voltage transmission line, according to a transmission line distributed parameter model. These equations are then differentially discretized in the time domain to establish first-order differential equations. These first-order differential equations are then matrix-transformed to obtain matrix-form equations, and spatial integration is performed on these matrix-form equations to obtain spatial integral equations. Based on the principle of voltage continuity along the transmission line, and using synchronous measurement information from both ends of the faulty line and the spatial integral equations, the location of the fault point in the high-voltage transmission line is determined. By performing matrix transformation and spatial integration on the differentially discretized first-order differential equations, and using synchronous measurement information from both ends of the faulty line to determine the fault point location, the algorithm is unconditionally stable, stable, and exhibits high ranging accuracy, high computational efficiency, and efficient fault location determination, unaffected by calculation conditions such as differential scheme and step size.

[0011] As a preferred approach, the transmission line telegraph equations are established based on the line structure and transmission line parameters of the high-voltage transmission line, specifically as follows:

[0012] Obtain the transmission line distributed parameter model of the high-voltage transmission line, and determine the line structure and transmission line parameters based on the transmission line distributed parameter model; among which, the transmission line parameters include transmission line length, resistance, inductance, conductance and capacitance;

[0013] Based on the line structure and transmission line parameters, the transmission line telegraphic equation is established, and the formula is as follows:

[0014]

[0015]

[0016] Where u(x,t) is the transmission line voltage at position x at time t, i(x,t) is the transmission line current at position x at time t, R is the resistance per unit length of the transmission line, L is the inductance per unit length of the transmission line, G is the conductance per unit length of the transmission line, C is the capacitance per unit length of the transmission line, and l is the length of the transmission line.

[0017] As a preferred approach, the transmission line telegraph equations are differentially discretized in the time domain to establish first-order differential equations, specifically:

[0018] Based on the known parameters, the transmission line telegraph equations are discretized by difference in the time domain to establish a first-order differential equation, the formula of which is:

[0019]

[0020]

[0021] Where Δt is the time step, u k =u(x,kΔt),i k = i(x,kΔt), where k is the number of calculation steps, k = 0, 1, 2, ... M;

[0022] Given the following parameters:

[0023] u(x,0)=h1(x)

[0024] i(x,0)=h2(x)

[0025] u(0,t)=u s (t)

[0026] i(l,t)=F2[u(l,t)]

[0027] Where h1(x) is the transmission line voltage at position x at t=0, h2(x) is the transmission line current at position x at t=0, and u s (t) is the input voltage at position x = 0, F2[u(l,t)] is the transmission line current at position x = l at time t, and l is the end of the transmission line.

[0028] As a preferred approach, the first-order differential equation is transformed into a matrix form to obtain the matrix equation, specifically:

[0029] The transmission line voltage and transmission line current are transformed into a matrix to obtain the first matrix, as shown in the formula:

[0030] X = (u1, ... u) M , i1, ... i M ) T

[0031] Where X is the first matrix;

[0032] The inductance per unit length of the transmission line, the current per unit length of the transmission line, the capacitance per unit length of the transmission line, and the voltage per unit length of the transmission line are transformed into a matrix to obtain a second matrix, as shown in the formula:

[0033]

[0034] Where F is the second matrix;

[0035] The transmission line parameters are transformed into a matrix to obtain a third matrix, as shown in the formula:

[0036]

[0037] Where H is the third matrix;

[0038] Based on the first, second, and third matrices, the first-order differential equation is transformed into matrix form, resulting in the matrix equation as follows:

[0039]

[0040] As a preferred approach, the matrix form equation is transformed by spatial integration to obtain the spatial integral equation, specifically:

[0041] According to the theory of differential equations, the matrix form equation is transformed by integration to obtain the first equation; specifically, the first equation is:

[0042]

[0043] Where H is the third matrix and X is the first matrix;

[0044] The spatial step size is calculated based on the length of the transmission line and the number of equal parts, using the following formula:

[0045] λ=l / M

[0046] Where λ is the spatial step size, M is the number of equal parts, and l is the length of the transmission line;

[0047] Based on the spatial step size, we obtain the spatial points with equal step sizes, specifically:

[0048] x j =jλ,j=0,1,2,L

[0049] Based on the spatial points with equal step sizes, the first equation is spatially transformed to obtain the second equation; specifically, the second equation is:

[0050]

[0051] When the preset conditions are met, the second equation is transformed into an equation to obtain the spatial integral equation; specifically, the spatial integral equation is:

[0052]

[0053] As a preferred method, the location of the fault point in the high-voltage transmission line is measured based on the principle of voltage continuity along the transmission line, synchronous measurement information at both ends of the faulty line, and spatial integral equations. Specifically:

[0054] The measurement values ​​at the beginning and end of the faulty line are collected synchronously, substituted into and solved by the spatial integral equation to calculate the first and second line voltages respectively; wherein, the measurement values ​​at the beginning include the voltage and current values ​​at the beginning, and the measurement values ​​at the end include the voltage and current values ​​at the end.

[0055] Based on the principle of voltage continuity along the transmission line, the first voltage along the line, and the second voltage along the line, the location of the fault point in the high-voltage transmission line is measured.

[0056] As a preferred method, based on the principle of voltage continuity along the transmission line, the first voltage along the line, and the second voltage along the line, the location of the fault point of the high-voltage transmission line is measured, specifically as follows:

[0057] Based on the characteristic that the voltage is equal at the fault point, the position function when the first line voltage and the second line voltage are equal is calculated using the following formula:

[0058] δ=|U mn (x,t)-U nm (x1,t)|

[0059] Where δ is the position x-position function, U mn (x,t) represents the first line voltage, U nm (x1,t) represents the second line voltage;

[0060] By differentiating the position function and calculating the position point at the minimum value of the position function, the location of the fault point of the high-voltage transmission line can be obtained.

[0061] To address the same technical problem, this invention also provides a time-domain fault location system for high-voltage transmission lines, comprising: a telegraph equation module, a differential equation module, a spatial integral equation module, and a location solving module.

[0062] Among them, the telegraph equation module is used to obtain and establish the telegraph equation of the transmission line based on the line structure and transmission line parameters of the high-voltage transmission line;

[0063] The differential equation module is used to discretize the transmission line telegraph equations in the time domain and establish first-order differential equations.

[0064] The spatial integral equation module is used to perform matrix transformation on first-order differential equations to obtain matrix form equations, and then perform spatial integral transformation on matrix form equations to obtain spatial integral equations.

[0065] The location module is used to measure the location of the fault point of a high-voltage transmission line by using the principle of voltage continuity along the transmission line, based on synchronous measurement information at both ends of the faulty line and spatial integral equations.

[0066] As a preferred embodiment, the spatial integral equation module includes a matrix transformation unit and a spatial integral transformation unit;

[0067] The matrix transformation unit is used to transform the first-order differential equation into a matrix form, specifically as follows:

[0068] The transmission line voltage and transmission line current are transformed into a matrix to obtain the first matrix, as shown in the formula:

[0069] X = (u1, ... u) M , i1, ... i M ) T

[0070] Where X is the first matrix;

[0071] The inductance per unit length of the transmission line, the current per unit length of the transmission line, the capacitance per unit length of the transmission line, and the voltage per unit length of the transmission line are transformed into a matrix to obtain a second matrix, as shown in the formula:

[0072]

[0073] Where F is the second matrix;

[0074] The transmission line parameters are transformed into a matrix to obtain a third matrix, as shown in the formula:

[0075]

[0076] Where H is the third matrix;

[0077] Based on the first, second, and third matrices, the first-order differential equation is transformed into matrix form, resulting in the matrix equation as follows:

[0078]

[0079] The spatial integral transformation unit is used to perform integral transformation on the matrix form equation according to the theory of differential equations, to obtain the first equation; wherein, the first equation is specifically:

[0080]

[0081] Wherein, H is the third matrix, and X is the first matrix;

[0082] The spatial step size is calculated based on the length of the transmission line and the number of equal parts, using the following formula:

[0083] λ=l / M

[0084] Where λ is the spatial step size, M is the number of equal parts, and l is the length of the transmission line;

[0085] Based on the spatial step size, we obtain the spatial points with equal step sizes, specifically:

[0086] x j =jλ,j=0,1,2,L s

[0087] Based on the spatial points with equal step sizes, the first equation is spatially transformed to obtain the second equation; specifically, the second equation is:

[0088]

[0089] When the preset conditions are met, the second equation is transformed into an equation to obtain the spatial integral equation; specifically, the spatial integral equation is:

[0090]

[0091] As a preferred solution, the location determination module includes a synchronous measurement unit and a fault point determination unit;

[0092] The synchronous measurement unit is used to synchronously collect the measurement values ​​at the beginning and end of the faulty line, substitute them into and solve the spatial integral equation to calculate the first line voltage and the second line voltage, respectively. The measurement values ​​at the beginning include the voltage value and the current value at the beginning, and the measurement values ​​at the end include the voltage value and the current value at the end.

[0093] The fault point determination unit is used to calculate the location function when the first line voltage value and the second line voltage are equal, based on the characteristic that the voltage is equal at the fault point. The formula is:

[0094] δ=|U mn (x,t)-U nm (x1,t)|

[0095] Where δ is the position x-position function, U mn (x,t) represents the first line voltage, U nm (x1,t) represents the second line voltage;

[0096] By differentiating the position function and calculating the position point at the minimum value of the position function, the location of the fault point of the high-voltage transmission line can be obtained. Attached Figure Description

[0097] Figure 1 : A flowchart illustrating an embodiment of a time-domain fault location method for high-voltage transmission lines provided by the present invention;

[0098] Figure 2 : A transmission line distributed parameter model diagram of an embodiment of a time-domain fault location method for high-voltage transmission lines provided by the present invention;

[0099] Figure 3 This is a transmission line fault diagram representing an embodiment of a time-domain fault location method for high-voltage transmission lines provided by the present invention.

[0100] Figure 4: A schematic diagram of an embodiment of a time-domain fault location system for high-voltage transmission lines provided by the present invention. Detailed Implementation

[0101] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0102] Example 1

[0103] Please refer to Figure 1 This is a flowchart illustrating a time-domain fault location method for high-voltage transmission lines according to an embodiment of the present invention. This time-domain fault location method is applicable to high-voltage transmission lines. This embodiment transforms the transmission line telegraph equation into a spatial integral equation through refined integration, efficiently determining the fault location of high-voltage transmission lines. It is unaffected by calculation conditions such as the difference scheme and step size, resulting in high location accuracy. The time-domain fault location method includes steps 101 to 104, each step as follows:

[0104] Step 101: Obtain and establish the transmission line telegraph equation based on the line structure and transmission line parameters of the high-voltage transmission line.

[0105] In this embodiment, based on the line structure and transmission line parameters of the high-voltage transmission line, the telegraph equation of the transmission line is established according to the transmission line distributed parameter model.

[0106] Optionally, step 101 specifically involves: obtaining the transmission line distribution parameter model of the high-voltage transmission line, and determining the line structure and transmission line parameters based on the transmission line distribution parameter model; wherein, the transmission line parameters include transmission line length, resistance, inductance, conductance and capacitance;

[0107] Based on the line structure and transmission line parameters, the transmission line telegraphic equation is established, and the formula is as follows:

[0108]

[0109]

[0110] Where u(x,t) is the transmission line voltage at position x at time t, i(x,t) is the transmission line current at position x at time t, R is the resistance per unit length of the transmission line, L is the inductance per unit length of the transmission line, G is the conductance per unit length of the transmission line, C is the capacitance per unit length of the transmission line, and l is the length of the transmission line.

[0111] In this embodiment, the power transmission line distributed parameter model is as follows: Figure 2 As shown in the figure, R is the resistance per unit length of the transmission line, L is the inductance per unit length of the transmission line, G is the conductance per unit length of the transmission line, C is the capacitance per unit length of the transmission line, and l is the length of the transmission line. The equation for the transmission line is as follows:

[0112]

[0113]

[0114] In the formula, u(x,t) is the transmission line voltage at location x at time t, and i(x,t) is the transmission line current at location x at time t. u and i are functions of space x and time t.

[0115] Step 102: Discretize the transmission line telegraph equations in the time domain to establish a first-order differential equation.

[0116] In this embodiment, the telegraph equation is discretized in the time domain to establish a first-order differential equation in space.

[0117] Optionally, step 102 specifically involves: based on the known parameter conditions, performing differential discretization on the transmission line telegraph equation in the time domain to establish a first-order differential equation, the formula of which is:

[0118]

[0119]

[0120] Where Δt is the time step, u k =u(x,kΔt),i k = i(x,kΔt), where k is the number of calculation steps, k = 0, 1, 2, ... M;

[0121] Given the following parameters:

[0122] u(x,0)=h1(x)

[0123] i(x,0)=h2(x)

[0124] u(0,t)=u s (t)

[0125] i(l,t)=F2[u(l,t)]

[0126] Where h1(x) is the transmission line voltage at position x at t=0, i.e., the voltage of the transmission line at position x at t=0; h2(x) is the transmission line current at position x at t=0, i.e., the current of the transmission line at position x at t=0; u s(t) is the input voltage at position x = 0, that is, the input voltage at x = 0; F2[u(l,t)] is the transmission line current at position x = l at time t, that is, the current at position x = l (the end of the line) at time t, where l is the end of the transmission line.

[0127] Step 103: Perform matrix transformation on the first-order differential equation to obtain the matrix form equation, and then perform spatial integration transformation on the matrix form equation to obtain the spatial integral equation.

[0128] In this embodiment, by solving the differential equation, the voltage and current values ​​at any point along the transmission line at any time can be obtained.

[0129] Optionally, the first-order differential equation can be transformed into a matrix form to obtain the matrix equation, specifically:

[0130] The transmission line voltage and transmission line current are transformed into a matrix to obtain the first matrix, as shown in the formula:

[0131] X = (u1, ... u) M , i1, ... i M ) T

[0132] Where X is the first matrix;

[0133] The inductance per unit length of the transmission line, the current per unit length of the transmission line, the capacitance per unit length of the transmission line, and the voltage per unit length of the transmission line are transformed into a matrix to obtain a second matrix, as shown in the formula:

[0134]

[0135] Where F is the second matrix;

[0136] The transmission line parameters are transformed into a matrix to obtain a third matrix, as shown in the formula:

[0137]

[0138] Where H is the third matrix;

[0139] Based on the first, second, and third matrices, the first-order differential equation is transformed into matrix form, resulting in the matrix equation as follows:

[0140]

[0141] Optionally, the matrix form equation can be transformed into a spatial integral equation to obtain a spatial integral equation, specifically:

[0142] According to the theory of differential equations, the matrix form equation is transformed by integration to obtain the first equation; specifically, the first equation is:

[0143]

[0144] Where H is the third matrix and X is the first matrix;

[0145] The spatial step size is calculated based on the length of the transmission line and the number of equal parts, using the following formula:

[0146] λ=l / M

[0147] Where λ is the spatial step size, M is the number of equal parts, and l is the length of the transmission line;

[0148] Based on the spatial step size, we obtain spatial points with equal step sizes, that is, a series of spatial points with equal step sizes λ, specifically:

[0149] x j =jλ,j=0,1,2,L

[0150] Based on the equal-step spatial points, the first equation is transformed to obtain the second equation. When x = jλ, the second equation is as follows:

[0151]

[0152] When the preset conditions are met, the second equation is transformed into an equation to obtain the spatial integral equation; specifically, the spatial integral equation is:

[0153]

[0154] In this embodiment, the preset condition is x. j <x≤x j+1 When x j <x≤x j+1 Then, the process of transforming the second equation into an equation is as follows:

[0155]

[0156] Step 104: Based on the principle of voltage continuity along the transmission line, and according to the synchronous measurement information at both ends of the faulty line and the spatial integral equation, the location of the fault point of the high-voltage transmission line is measured.

[0157] In this embodiment, the location of the fault point is determined by using synchronous measurement information at both ends of the faulty line and based on the principle of voltage continuity along the transmission line.

[0158] Optionally, step 104 specifically includes steps 1041 to 1042, each of which is as follows:

[0159] Step 1041: Synchronously collect the measured values ​​at the beginning and end of the faulty line, substitute them into and solve the spatial integral equation, and calculate the first line voltage and the second line voltage respectively; wherein, the measured values ​​at the beginning include the voltage value and the current value at the beginning, and the measured values ​​at the end include the voltage value and the current value at the end.

[0160] In this embodiment, using the synchronous measurement information at both ends of the faulty line (referring to the voltage value u(0,t) and current value i(0,t) at the beginning of the line x=0, and the voltage value u(l,t) and current value i(l,t) at the end of the line x=l), the voltage and current values ​​along the transmission line based on the measurement data at both ends can be calculated respectively. For example, a faulty transmission line... Figure 3 As shown, in the transmission line MN with a fault, when a fault occurs at point F, voltage and current values ​​are simultaneously collected at terminals M and N of the transmission line. Using the collected data from terminals M and N, the first line voltage U at any point on segments MF and NF at any given time is calculated according to the spatial integral equation. mn (x,t) and the second line voltage U nm (x1,t), where x is the distance from a point on line segment MF to end M, and x1 is the distance from a point on line segment NF to end N. Because of the short-circuit current at the fault, the line voltage and current distribution calculated from the voltage and current values ​​at point M is correct in segment MF but incorrect in segment FN; similarly, the line voltage and current distribution calculated from the voltage and current values ​​at point N is correct in segment NF but incorrect in segment MF.

[0161] Step 1042: Based on the principle of voltage continuity along the transmission line, the first voltage along the line, and the second voltage along the line, measure the location of the fault point of the high-voltage transmission line.

[0162] In this embodiment, based on the principle of voltage continuity along the transmission line, the location of the fault point can be determined by calculating the voltage along the transmission line from the measurement data at both ends of the line, since the voltage is equal at the fault point.

[0163] Optionally, step 1042 specifically involves: based on the characteristic that the voltage is equal at the fault point, calculating the position function when the first line voltage value and the second line voltage are equal, using the formula:

[0164] δ=|U mn (x,t)-U nm (x1,t)|

[0165] Where δ is the position x-position function, U mn (x,t) represents the first line voltage, U nm (x1,t) represents the second line voltage;

[0166] By differentiating the position function and calculating the position point at the minimum value of the position function, the location of the fault point of the high-voltage transmission line can be obtained.

[0167] In this embodiment, based on the principle of voltage continuity in transmission lines, the following situation only exists at fault point F:

[0168] U mn (x,t)=U nm (x1,t)

[0169] Let δ be the difference between the first and second line-side voltages, that is:

[0170] δ=|U mn (x,t)-U nm (x1,t)|

[0171] δ is a function of position x. Theoretically, δ is 0 at the fault point. However, in practical engineering, calculation errors are unavoidable, resulting in a very small value. The fault point can be determined by finding the minimum value of x at δ through differentiation.

[0172] In implementing this embodiment of the invention, a transmission line telegraph equation is established based on the transmission line distributed parameter model of a high-voltage transmission line; the transmission line telegraph equation is differentially discretized in the time domain to establish a first-order differential equation; the first-order differential equation is matrix-transformed to obtain a matrix form equation, and the matrix form equation is spatially integrated to obtain a spatial integral equation; based on the principle of voltage continuity along the transmission line, and according to the synchronous measurement information at both ends of the faulty line and the spatial integral equation, the location of the fault point of the high-voltage transmission line is determined.

[0173] By performing matrix transformation and spatial integration on the first-order differential equation after differential separation, and based on the synchronous measurement information at both ends of the faulty line, the location of the fault point in the high-voltage transmission line can be determined. The algorithm is unconditionally stable, unaffected by the differential scheme and step size, and has high ranging accuracy, high computational efficiency, and efficient fault point location determination.

[0174] Example 2

[0175] Accordingly, see Figure 4 , Figure 4 This is a schematic diagram of a second embodiment of a time-domain fault location system for high-voltage transmission lines provided by the present invention. Figure 4 As shown, the time-domain fault location system for high-voltage transmission lines includes a telegraph equation module 401, a differential equation module 402, a spatial integral equation module 403, and a location solving module 404.

[0176] Among them, the telegraph equation module 401 is used to obtain and establish the telegraph equation of the transmission line based on the line structure and transmission line parameters of the high-voltage transmission line;

[0177] The differential equation module 402 is used to perform differential discretization of the transmission line telegraph equation in the time domain to establish a first-order differential equation;

[0178] The spatial integral equation module 403 is used to perform matrix transformation on the first-order differential equation to obtain the matrix form equation, and then perform spatial integral transformation on the matrix form equation to obtain the spatial integral equation.

[0179] The spatial integral equation module 403 includes a matrix transformation unit 4031 and a spatial integral transformation unit 4032;

[0180] The matrix transformation unit 4031 is used to transform the first-order differential equation into a matrix form, specifically as follows:

[0181] The transmission line voltage and transmission line current are transformed into a matrix to obtain the first matrix, as shown in the formula:

[0182] X = (u1, ... u) M , i1, ... i M ) T

[0183] Where X is the first matrix;

[0184] The inductance per unit length of the transmission line, the current per unit length of the transmission line, the capacitance per unit length of the transmission line, and the voltage per unit length of the transmission line are transformed into a matrix to obtain a second matrix, as shown in the formula:

[0185]

[0186] Where F is the second matrix;

[0187] The transmission line parameters are transformed into a matrix to obtain a third matrix, as shown in the formula:

[0188]

[0189] Where H is the third matrix;

[0190] Based on the first, second, and third matrices, the first-order differential equation is transformed into matrix form, resulting in the matrix equation as follows:

[0191]

[0192] The spatial integral transformation unit 4032 is used to perform integral transformation on the matrix form equation according to the theory of differential equations to obtain the first equation; wherein, the first equation is specifically:

[0193]

[0194] Wherein, H is the third matrix, and X is the first matrix;

[0195] The spatial step size is calculated based on the length of the transmission line and the number of equal parts, using the following formula:

[0196] λ=l / M

[0197] Where λ is the spatial step size, M is the number of equal parts, and l is the length of the transmission line;

[0198] Based on the spatial step size, we obtain the spatial points with equal step sizes, specifically:

[0199] x j =jλ,j=0,1,2,L

[0200] Based on the spatial points with equal step sizes, the first equation is spatially transformed to obtain the second equation; specifically, the second equation is:

[0201]

[0202] When the preset conditions are met, the second equation is transformed into an equation to obtain the spatial integral equation; specifically, the spatial integral equation is:

[0203]

[0204] The location module 404 is used to measure the location of the fault point of the high-voltage transmission line by using the principle of voltage continuity along the transmission line, based on the synchronous measurement information at both ends of the faulty line and the spatial integral equation.

[0205] The location determination module 404 includes a synchronous measurement unit 4041 and a fault point determination unit 4042;

[0206] The synchronous measurement unit 4041 is used to synchronously acquire the measurement values ​​at the beginning and end of the faulty line, substitute them into and solve the spatial integral equation, and calculate the first line voltage and the second line voltage respectively. The measurement values ​​at the beginning include the voltage value and the current value at the beginning, and the measurement values ​​at the end include the voltage value and the current value at the end.

[0207] The fault point determination unit 4042 is used to calculate the position function when the first line voltage value and the second line voltage are equal, based on the characteristic that the voltage is equal at the fault point. The formula is as follows:

[0208] δ=|U mn (x,t)-U nm (x1,t)|

[0209] Where δ is the position x-position function, U mn (x,t) represents the first line voltage, U nm(x1,t) represents the second line voltage;

[0210] By differentiating the position function and calculating the position point at the minimum value of the position function, the location of the fault point of the high-voltage transmission line can be obtained.

[0211] The aforementioned time-domain fault location system for high-voltage transmission lines can implement the time-domain fault location method for high-voltage transmission lines described in the above-described method embodiments. The options in the above method embodiments are also applicable to this embodiment and will not be detailed here. The remaining contents of this application's embodiments can be referred to the contents of the above method embodiments, and will not be repeated in this embodiment.

[0212] While the frequency domain method is simple and reliable in implementing the embodiments of this invention, its measurement accuracy is difficult to guarantee. The traveling wave method is unaffected by transition resistance, but wavefront extraction and wave velocity determination are difficult, and the expensive equipment limits its application. The conventional time domain method suffers from computational accuracy and stability greatly affected by the differential scheme and computational step size. However, the time-domain fault location system for high-voltage transmission lines proposed in this invention is a semi-analytical time-domain method with unconditional algorithm stability and high location accuracy. Its application is unrestricted and can be widely promoted and used.

[0213] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A time-domain fault location method for high-voltage transmission lines, characterized in that, include: Based on the line structure and transmission line parameters of the high-voltage transmission line, establish the transmission line telegraph equation; The process of obtaining and establishing the transmission line telegraph equation based on the line structure and transmission line parameters of the high-voltage transmission line is as follows: Obtain the transmission line distribution parameter model of the high-voltage transmission line, and determine the line structure and transmission line parameters based on the transmission line distribution parameter model; wherein, the transmission line parameters include transmission line length, resistance, inductance, conductance and capacitance; Based on the line structure and transmission line parameters, the transmission line telegraphic equation is established, and the formula is as follows: in, u ( x , t ) is the location x In time t Transmission line voltage at any given time i ( x , t ) is the location x In time t The current in the transmission line at any given time is given by R, the resistance per unit length of the transmission line is given by L, the inductance per unit length of the transmission line is given by G, the conductance per unit length of the transmission line is given by C, and the capacitance per unit length of the transmission line is given by C. l The length of the transmission line; The transmission line telegraph equations are discretized by difference in the time domain to establish a first-order differential equation; The first-order differential equation is transformed into a matrix form to obtain a matrix form equation, and then the matrix form equation is transformed into a space integral equation to obtain a space integral equation. Based on the principle of voltage continuity along the transmission line, and according to the synchronous measurement information at both ends of the faulty line and the spatial integral equation, the location of the fault point of the high-voltage transmission line is measured.

2. The time-domain fault location method for high-voltage transmission lines as described in claim 1, characterized in that, The step of discretizing the transmission line telegraph equation in the time domain to establish a first-order differential equation is as follows: Based on the known parameters, the transmission line telegraph equation is discretized by difference in the time domain to establish the first-order differential equation, as shown in the following formula: Among them,  t For time step, , k is the number of calculation steps. k =0,1,2,…M; The known parameter conditions are as follows: in, h 1( x ) is the location x The transmission line voltage at t=0 h 2( x ) is the location x The transmission line current at t=0 u s ( t ) is the location x =0 input voltage, F2[ u ( l , t )] is in position x = l The transmission line current at time t. l This refers to the end of a power transmission line.

3. The time-domain fault location method for high-voltage transmission lines as described in claim 2, characterized in that, The process of transforming the first-order differential equation into a matrix form to obtain the matrix equation is as follows: The transmission line voltage and the transmission line current are transformed into a matrix to obtain the first matrix, as shown in the formula: in, This is the first matrix; The inductance per unit length of the transmission line, the current in the transmission line, the capacitance per unit length of the transmission line, and the voltage in the transmission line are transformed into a matrix to obtain a second matrix, as shown in the formula: Where is the second matrix; The transmission line parameters are transformed into a matrix to obtain a third matrix, as shown in the formula: Wherein, H is the third matrix; Based on the first matrix, the second matrix, and the third matrix, the first-order differential equation is transformed into matrix form, resulting in the matrix form equation, specifically: 。 4. The time-domain fault location method for high-voltage transmission lines as described in claim 3, characterized in that, The spatial integral transformation of the matrix form equation to obtain the spatial integral equation is specifically as follows: According to the theory of differential equations, the matrix form equation is integrally transformed to obtain the first equation; wherein, the first equation is specifically: Where H is the third matrix, This is the first matrix; The spatial step size is calculated based on the length and fractional division of the transmission line, using the following formula: λ=l / M in,  Let the spatial step size be denoted as . M The number of equal parts, l The length of the transmission line; Based on the spatial step size, the equal-step spatial points are obtained, specifically: Based on the equal-step spatial points, the first equation is spatially transformed to obtain the second equation; wherein, the second equation is specifically: When the preset conditions are met, the second equation is transformed into an equation to obtain the spatial integral equation; wherein, the spatial integral equation is specifically: 。 5. The time-domain fault location method for high-voltage transmission lines as described in claim 1, characterized in that, The location of the fault point in the high-voltage transmission line is determined by utilizing the principle of voltage continuity along the transmission line, based on synchronous measurement information at both ends of the faulty line and the spatial integral equation. Specifically: The measurement values ​​at the beginning and end of the faulty line are collected synchronously, substituted into and solved by the spatial integral equation to calculate the first line voltage and the second line voltage, respectively; wherein, the measurement value at the beginning includes the voltage value and the current value at the beginning, and the measurement value at the end includes the voltage value and the current value at the end. Based on the principle of voltage continuity along the transmission line, the first voltage along the line, and the second voltage along the line, the location of the fault point of the high-voltage transmission line is measured.

6. The time-domain fault location method for high-voltage transmission lines as described in claim 5, characterized in that, The location of the fault point in the high-voltage transmission line is measured based on the principle of voltage continuity along the transmission line, the first voltage along the line, and the second voltage along the line. Specifically: Based on the characteristic that the voltage is equal at the fault point, the position function is calculated when the first line voltage value and the second line voltage value are equal. The formula is as follows: Where δ represents the position. x The position function U mn ( x,t ) represents the first line voltage. U nm ( x 1, t ) represents the second line voltage; The location of the fault point of the high-voltage transmission line is obtained by taking the derivative of the position function and calculating the position point at the minimum value of the position function.

7. A time-domain fault location system for high-voltage transmission lines, characterized in that, include: Telegraph equation module, differential equation module, spatial integral equation module, and solution location module; The telegraph equation module is used to acquire and establish the transmission line telegraph equation based on the line structure and transmission line parameters of the high-voltage transmission line, specifically as follows: Obtain the transmission line distribution parameter model of the high-voltage transmission line, and determine the line structure and transmission line parameters based on the transmission line distribution parameter model; wherein, the transmission line parameters include transmission line length, resistance, inductance, conductance and capacitance; Based on the line structure and transmission line parameters, the transmission line telegraphic equation is established, and the formula is as follows: in, u ( x , t ) is the location x In time t Transmission line voltage at any given time i ( x , t ) is the location x In time t The current in the transmission line at any given time is given by R, the resistance per unit length of the transmission line is given by L, the inductance per unit length of the transmission line is given by G, the conductance per unit length of the transmission line is given by C, and the capacitance per unit length of the transmission line is given by C. l The length of the transmission line; The differential equation module is used to perform differential discretization on the transmission line telegraph equation in the time domain to establish a first-order differential equation. The spatial integral equation module is used to perform matrix transformation on the first-order differential equation to obtain a matrix form equation, and to perform spatial integral transformation on the matrix form equation to obtain a spatial integral equation. The location-finding module is used to measure the location of the fault point of the high-voltage transmission line by using the principle of voltage continuity along the transmission line, based on the synchronous measurement information at both ends of the faulty line and the spatial integral equation.

8. The time-domain fault location system for high-voltage transmission lines as described in claim 7, characterized in that, The spatial integral equation module includes a matrix transformation unit and a spatial integral transformation unit; The matrix transformation unit is used to transform the first-order differential equation into a matrix form, specifically as follows: The transmission line voltage and the transmission line current are transformed into a matrix to obtain the first matrix, as shown in the formula: in, This is the first matrix; The inductance per unit length of the transmission line, the current in the transmission line, the capacitance per unit length of the transmission line, and the voltage in the transmission line are transformed into a matrix to obtain a second matrix, as shown in the formula: Where is the second matrix; The transmission line parameters are transformed into a matrix to obtain a third matrix, as shown in the formula: Wherein, H is the third matrix; Based on the first matrix, the second matrix, and the third matrix, the first-order differential equation is transformed into matrix form, resulting in the matrix form equation, specifically: The spatial integral transformation unit is used to perform integral transformation on the matrix form equation according to the theory of differential equations to obtain a first equation; wherein, the first equation is specifically: Where H is the third matrix, This is the first matrix; The spatial step size is calculated based on the length and fractional division of the transmission line, using the following formula: λ=l / M in,  Let the spatial step size be denoted as . M The number of equal parts, l The length of the transmission line; Based on the spatial step size, the equal-step spatial points are obtained, specifically: Based on the equal-step spatial points, the first equation is spatially transformed to obtain the second equation; wherein, the second equation is specifically: When the preset conditions are met, the second equation is transformed into an equation to obtain the spatial integral equation; wherein, the spatial integral equation is specifically: 。 9. The time-domain fault location system for high-voltage transmission lines as described in claim 7, characterized in that, The location determination module includes a synchronous measurement unit and a fault point determination unit; The synchronous measurement unit is used to synchronously collect the measurement values ​​at the beginning and end of the faulty line, substitute them into and solve the spatial integral equation, and calculate the first line voltage and the second line voltage respectively; wherein, the measurement value at the beginning includes the voltage value and the current value at the beginning, and the measurement value at the end includes the voltage value and the current value at the end. The fault point determination unit is used to calculate the position function when the first line voltage value and the second line voltage value are equal, based on the characteristic that the voltage is equal at the fault point. The formula is: Where δ represents the position. x The position function U mn ( x,t ) represents the first line voltage. U nm ( x 1, t ) represents the second line voltage; The location of the fault point of the high-voltage transmission line is obtained by taking the derivative of the position function and calculating the position point at the minimum value of the position function.

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